The development of the
Sunny Hive was started in 2019, and the first actual results were obtained only
in 2024. During all three years, the hive design itself was continuously
improved, and studies were carried out on the temperatures created by the hive
inside the bee nest and on the effect of temperature on bees and brood.
As of today, the latest
version of the hive is fully functional, although in some cases it requires the
beekeeper's attention. During the summer season of 2025, the Solar Apiary
showed fairly good results. None of the colonies were treated against Varroa
mites from October 2024 to October 2025, and their infestation levels were
quite acceptable. The year 2025 had several temperature extremes, but overall
there were not many hot and sunny days.
The summer season of 2026
was warmer and sunnier than the summer season of 2025. Our observations began
in March and lost their significance at the end of August–beginning of
September (Fig. 1).
At the end of April, the
Solar Apiary produced the first bee packages with queens from 2025. In June,
some colonies produced packages again, this time with young queens from 2026.
Some of the colonies that produced only the first packages in April collected
2–3 honey supers per colony at the stationary apiary.
Figure 1. Air temperature
between the brood frames in the bee nest in control hive No. 13
Throughout the season,
experiments were conducted to measure temperatures inside the hive under
various conditions of solar activity and air temperature. An experiment was
also carried out involving direct monitoring of the temperature in a frame
containing capped brood.
The results confirmed the
previous data. In a full-strength bee colony with a sufficient amount of brood,
honey and pollen stores, and a sufficient number of bees, the threshold
temperature at which it is not necessary to cover the protective shields is +28°C,
provided that the sky is clear. Naturally, the hive must be located in a place
exposed to sunlight.
At the same time, under the
same conditions, colonies occupying only 4–5 frames may die, especially if the
frames are new, partially filled with honey, and the foundation is too soft.
During the experiment, foundation made in Tambov melted and, under the weight
of young honey, collapsed onto the bottom of the hive. All frames, including
those containing brood, were damaged. The bees and the queen died.
Thus, when operating a Sunny
Hive, it is very important to maintain a temperature range that is safe for
bees. The air temperature in the nest of a full-strength colony should never
exceed +40–41°C, taking into account that the temperature of
brood combs is generally somewhat lower than the air temperature inside the
hive. At the same time, a comb temperature of +37–38°C is
quite sufficient to suppress the development of the Varroa mite population.
In the 2026 season, brood
was exposed to high temperatures more frequently than in 2025, although the
peak temperature values themselves were lower. There were six sufficiently
strong and prolonged exposure events. During these events, peak air
temperatures between the brood frames reached +39–40°C, but
most readings were close to +38°C. There were three
additional, less intense but still significant exposure events. At those times,
nest temperatures were within approximately +37°C.
To obtain data on the
effect of the hives on the bee colonies, alkaline washes were performed at the
end of September 2026, when no brood remained in the colonies.
The wash results showed
that dividing the colonies according to their purpose — into colonies
used as sources of splits/nuc colonies and honey-producing
colonies — had a significant effect on the Varroa infestation level of
the colonies.
The colonies that produced
two splits and raised emergency queens had the lowest infestation levels at the
end of the season — less than 1%.
The colonies that produced
one split at the end of April and subsequently produced 2–3 honey supers showed
infestation levels of 2–2.5% (with honey extraction performed
once, at the end of the main honey flow), except for colony No. 13, which was
continuously involved in various temperature experiments. Its infestation level
was the highest, at 9.6%.
In our opinion, the reason
for this was that on the hottest days experiments were conducted with the
shields protecting the hive from sunlight under high outdoor temperatures.
Figure 2. Graphs showing
Varroa infestation levels of the colonies in 2026 and comparison with 2025
As a result, it can be
stated that the average Varroa infestation level in the Solar Apiary, calculated
for the 7 colonies that did not change hives, were not destroyed, and
were not repopulated with new colonies, decreased by almost 2.1
times, from 6.53% to 3.05%.
Colony No. 7, which was not
treated with Bipin in 2025, showed an increase in infestation of:
6.3 / 1.4 = 4.5
times
instead of the
theoretically expected 64-fold increase under conventional
management. It is possible that the figure of 64 could have been somewhat
lower, taking into account the production of splits and the raising of
emergency queens.
But most importantly,
overall the apiary became approximately twice less infested
than it was at the end of the previous year, even though one autumn treatment
with Bipin was carried out.
This means that with the
use of Solar Hives year after year, it may be possible to reduce Varroa
infestation in apiaries to practically zero.
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